The invention pertains to a microfiche reader and more particularly to a control device adapted to locate individual images to be viewed on a microfiche.
Information storage and retrieval on microfiches are commonly used in practice. The microfiches known in the art usually have a size of 105.times.148 mm but may also have different dimensions, such as e.g. 180.times.240 mm. In a reading device known in practice, a microfiche is shifted along two mutually normal coordinate axes. In order to retrieve individual images to be viewed on the microfiche one should first of all to locate a first of images on a selected microfiche. In the commonly known microfiches the symbols or indica indicating letters or alphabetic signs and positioned in horizontally extending rows of images. When the desirable region of rows is found one actuates the respective button on a keyboard carrying alphabetic symbols and the microfiche is moved toward a lens system having an optical axis. The first image of the selected horizontal row appears then on a screen of the reading device. This image indicates an index field.
To further locate the desired individual image one must retrieve this image in a selected row of numeric keyboard as to move the microfiche along a second cordinate in order to place the desired section of the microfiche so as to intersect the optical axis of the lens system. As soon as the desired image is found on the numeric keyboard, the corresponding button on the numeric keyboard is pushed so that the selected image is automatically called up.
The above-described system of locating of individual images to be viewed on a microfiche enables one to substantially more quickly retrieve an individual image from microfiches that it is possible to do from micro films. However, in practice there is a need to further accelerate the process of locating individual images on a microfiche.